Study of demolding characteristics in step-and-repeat ultraviolet nanoimprinting

Ultraviolet (UV) nanoimprinting includes a contact process necessary for transferring nanoscale features from a mold to a UV-curable resist coated on a substrate. The demolding that comes with the contact process is a source of defects, and an obstacle to be overcome for nanodevice fabrications. In this study, we aim to execute more than 10000 times of step-and-repeat UV nanoimprinting with a single mold, tracing demolding forces and water contact angles of the mold surface as the indication of mold-resist/substrate interface and mold degradation. A condensable gas, a UV-curable resist, and a fluorosurfactant were considered in this study. It was revealed that 1,1,1,3,3-pentafluoropropane (PFP) or HFC-245fa, which is the common industrial name, as a condensable gas and a type of fluorosurfactant played an important role in minimizing the demolding impact and thus helped in increasing mold lifetime. The surfactant-added resists performed 6500 imprinting steps in PFP.